Devices for converting electrical signals into optical signals are known. Semiconductor laser diodes are quite useful for converting electrical signals to a modulated light beam as they can be modulated at extremely high rates. In a high speed fiber optic laser module, an electrical input signal is converted into an optical output signal via a laser diode, and the output is then transmitted via the optical fiber. An example of such a module is described in U.S. Pat. No. 4,802,178 to Ury (incorporated by reference herein).
Alignment of the optical fiber with the laser diode in fiber optic modules is a critical, but often difficult task, in part because of the extremely small size of the laser and the optical fiber. Temperature changes compound the problem, as thermal stresses can build up between the optical fiber and other parts of the module and force the fiber out of alignment. Additionally, the noise in the modulated signal of the laser is increased by light which gets reflected back toward the laser, including reflections from the end of the optical fiber. Accordingly, there is a need for a laser modulation device which is easy to align and maintain in an aligned configuration. Such a device should reduce or relieve the build-up of thermal stress on an attached optical fiber and should reduce noise of the laser diode without the device. Preferably, the device should be capable of manufacture with or without the optical fiber that is ultimately used for the transmission of output signals, so that the customer of the device may install his own fiber.